diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index a0d1079072a..3bb84eac492 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -4374,9 +4374,10 @@ abstract class CommonObject
 	 *  Check is done into this->childtables. There is no check into llx_element_element.
 	 *
 	 *  @param	int		$id			Force id of object
+	 *  @param	int		$entity		Force entity to check
 	 *  @return	int					<0 if KO, 0 if not used, >0 if already used
 	 */
-	public function isObjectUsed($id = 0)
+	public function isObjectUsed($id = 0, $entity = 0)
 	{
 		global $langs;
 
@@ -4399,11 +4400,25 @@ abstract class CommonObject
 
 		// Test if child exists
 		$haschild = 0;
-		foreach ($arraytoscan as $table => $elementname) {
+		foreach ($arraytoscan as $table => $element) {
 			//print $id.'-'.$table.'-'.$elementname.'<br>';
-			// Check if third party can be deleted
-			$sql = "SELECT COUNT(*) as nb from ".$this->db->prefix().$table;
-			$sql .= " WHERE ".$this->fk_element." = ".((int) $id);
+			// Check if element can be deleted
+			$sql = "SELECT COUNT(*) as nb";
+			$sql.= " FROM ".$this->db->prefix().$table." as c";
+			if (!empty($element['parent']) && !empty($element['parentkey'])) {
+				$sql.= ", ".$this->db->prefix().$element['parent']." as p";
+			}
+			$sql.= " WHERE c.".$this->fk_element." = ".((int) $id);
+			if (!empty($element['parent']) && !empty($element['parentkey'])) {
+				$sql.= " AND c.".$element['parentkey']." = p.rowid";
+			}
+			if (!empty($entity)) {
+				if (!empty($element['parent']) && !empty($element['parentkey'])) {
+					$sql.= " AND p.entity = ".((int) $entity);
+				} else {
+					$sql.= " AND c.entity = ".((int) $entity);
+				}
+			}
 			$resql = $this->db->query($sql);
 			if ($resql) {
 				$obj = $this->db->fetch_object($resql);
@@ -4411,11 +4426,12 @@ abstract class CommonObject
 					$langs->load("errors");
 					//print 'Found into table '.$table.', type '.$langs->transnoentitiesnoconv($elementname).', haschild='.$haschild;
 					$haschild += $obj->nb;
-					if (is_numeric($elementname)) {	// old usage
-						$this->errors[] = $langs->transnoentities("ErrorRecordHasAtLeastOneChildOfType", method_exists($this, 'getNomUrl') ? $this->getNomUrl() : $this->ref, $table);
-					} else // new usage: $elementname=Translation key
-					{
-						$this->errors[] = $langs->transnoentities("ErrorRecordHasAtLeastOneChildOfType", method_exists($this, 'getNomUrl') ? $this->getNomUrl() : $this->ref, $langs->transnoentitiesnoconv($elementname));
+					if (is_numeric($element)) {	// very old usage array('table1', 'table2', ...)
+						$this->errors[] = $langs->transnoentitiesnoconv("ErrorRecordHasAtLeastOneChildOfType", method_exists($this, 'getNomUrl') ? $this->getNomUrl() : $this->ref, $table);
+					} elseif (is_string($element)) { // old usage array('table1' => 'TranslateKey1', 'table2' => 'TranslateKey2', ...)
+						$this->errors[] = $langs->transnoentitiesnoconv("ErrorRecordHasAtLeastOneChildOfType",  method_exists($this, 'getNomUrl') ? $this->getNomUrl() : $this->ref, $langs->transnoentitiesnoconv($element));
+					} else { // new usage: $element['name']=Translation key
+						$this->errors[] = $langs->transnoentitiesnoconv("ErrorRecordHasAtLeastOneChildOfType",  method_exists($this, 'getNomUrl') ? $this->getNomUrl() : $this->ref, $langs->transnoentitiesnoconv($element['name']));
 					}
 					break; // We found at least one, we stop here
 				}
diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 6e97e80fece..d308ceb8e53 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -64,13 +64,13 @@ class Product extends CommonObject
 	 * @var array	List of child tables. To test if we can delete object.
 	 */
 	protected $childtables = array(
-		'supplier_proposaldet',
-		'propaldet',
-		'commandedet',
-		'facturedet',
-		'contratdet',
-		'facture_fourn_det',
-		'commande_fournisseurdet'
+		'supplier_proposaldet' => array('name' => 'SupplierProposal', 'parent' => 'supplier_proposal', 'parentkey' => 'fk_supplier_proposal'),
+		'propaldet' => array('name' => 'Proposal', 'parent' => 'propal', 'parentkey' => 'fk_propal'),
+		'commandedet' => array('name' => 'Order', 'parent' => 'commande', 'parentkey' => 'fk_commande'),
+		'facturedet' => array('name' => 'Invoice', 'parent' => 'facture', 'parentkey' => 'fk_facture'),
+		'contratdet' => array('name' => 'Contract', 'parent' => 'contrat', 'parentkey' => 'fk_contrat'),
+		'facture_fourn_det' => array('name' => 'SupplierInvoice', 'parent' => 'facture_fourn', 'parentkey' => 'fk_facture_fourn'),
+		'commande_fournisseurdet' => array('name' => 'SupplierOrder', 'parent' => 'commande_fournisseur', 'parentkey' => 'fk_commande')
 	);
 
 	/**
diff --git a/htdocs/projet/class/task.class.php b/htdocs/projet/class/task.class.php
index 443e945aecb..d99b13b29c7 100644
--- a/htdocs/projet/class/task.class.php
+++ b/htdocs/projet/class/task.class.php
@@ -59,7 +59,9 @@ class Task extends CommonObjectLine
 	/**
 	 * @var array	List of child tables. To test if we can delete object.
 	 */
-	protected $childtables = array('projet_task_time');
+	protected $childtables = array(
+		'projet_task_time' => array('name' => 'Task', 'parent' => 'projet_task', 'parentkey' => 'fk_task')
+	);
 
 	/**
 	 * @var int ID parent task
diff --git a/htdocs/societe/class/societe.class.php b/htdocs/societe/class/societe.class.php
index 89eeeaca8e5..7fab734a12c 100644
--- a/htdocs/societe/class/societe.class.php
+++ b/htdocs/societe/class/societe.class.php
@@ -73,18 +73,18 @@ class Societe extends CommonObject
 	 * @var array	List of child tables. To test if we can delete object.
 	 */
 	protected $childtables = array(
-		"supplier_proposal" => 'SupplierProposal',
-		"propal" => 'Proposal',
-		"commande" => 'Order',
-		"facture" => 'Invoice',
-		"facture_rec" => 'RecurringInvoiceTemplate',
-		"contrat" => 'Contract',
-		"fichinter" => 'Fichinter',
-		"facture_fourn" => 'SupplierInvoice',
-		"commande_fournisseur" => 'SupplierOrder',
-		"projet" => 'Project',
-		"expedition" => 'Shipment',
-		"prelevement_lignes" => 'DirectDebitRecord',
+		'supplier_proposal' => array('name' => 'SupplierProposal'),
+		'propal' => array('name' => 'Proposal'),
+		'commande' => array('name' => 'Order'),
+		'facture' => array('name' => 'Invoice'),
+		'facture_rec' => array('name' => 'RecurringInvoiceTemplate'),
+		'contrat' => array('name' => 'Contract'),
+		'fichinter' => array('name' => 'Fichinter'),
+		'facture_fourn' => array('name' => 'SupplierInvoice'),
+		'commande_fournisseur' => array('name' => 'SupplierOrder'),
+		'projet' => array('name' => 'Project'),
+		'expedition' => array('name' => 'Shipment'),
+		'prelevement_lignes' => array('name' => 'DirectDebitRecord'),
 	);
 
 	/**
@@ -92,22 +92,22 @@ class Societe extends CommonObject
 	 *               if name like with @ClassName:FilePathClass:ParentFkFieldName' it will call method deleteByParentField (with parentId as parameters) and FieldName to fetch and delete child object
 	 */
 	protected $childtablesoncascade = array(
-		"societe_prices",
-		"societe_address",
-		"product_fournisseur_price",
-		"product_customer_price_log",
-		"product_customer_price",
-		"@Contact:/contact/class/contact.class.php:fk_soc",
-		"adherent",
-		"societe_account",
-		"societe_rib",
-		"societe_remise",
-		"societe_remise_except",
-		"societe_commerciaux",
-		"categorie",
-		"notify",
-		"notify_def",
-		"actioncomm",
+		'societe_prices',
+		'societe_address',
+		'product_fournisseur_price',
+		'product_customer_price_log',
+		'product_customer_price',
+		'@Contact:/contact/class/contact.class.php:fk_soc',
+		'adherent',
+		'societe_account',
+		'societe_rib',
+		'societe_remise',
+		'societe_remise_except',
+		'societe_commerciaux',
+		'categorie',
+		'notify',
+		'notify_def',
+		'actioncomm',
 	);
 
 	/**